KR20060108617A - Voltage converters, power management devices and mobile devices including them - Google Patents

Abstract

The voltage converter includes an inductive circuit L that stores energy during the inductive magnetization mode and delivers energy during the inductive demagnetization mode. The voltage converter also has at least two non-inverting branches 12, 13, 14 for providing at least two non-inverting output voltages Va, Vb, Vc, and an inverting branch 15 for providing an inverted output voltage. It includes. The inverting 15 and non-inverting branches 12, 13 and 14 are connected side by side to the output terminal 10 of the inductive circuit L. The inductive circuit is arranged to transfer energy to one of the inverted branch 15 and the at least two non-inverted branches 12, 13, 14. In this way, the inversion voltage Vinv and the corresponding non-inverting output voltages Va, Vb, Vc of the at least two non-inverting branches 12, 13, 14 have opposite polarities and have substantially the same magnitude. .

Description

Voltage converters, power management and mobile devices including them {VOLTAGE CONVERTER}

The present invention relates to a mobile device including a voltage converter, a power management device and a voltage converter.

The invention can be used, for example, in a power supply or in a mobile device (eg, mobile phone, PDA or laptop). Voltage converters are commonly used to derive multiple DC output voltages from a DC input voltage source. This output voltage can have a higher voltage level than the DC input voltage. The voltage converter is also commonly referred to as a DCDC voltage converter or switched mode power supply (SMPS). DCDC converters are generally well known in the art. The voltage converter comprises energy storage means, such as an intert, which stores energy obtained from a DC input voltage source. This energy is later used to generate and maintain multiple output voltages. The energy storage means are charged and discharged periodically and the energy flow from the energy storage means to the output of the voltage converter is regulated by a programmable switch device. It is also generally known in the art that a negative voltage may be provided by using an inverting circuit connected to any of the output stages of the voltage converter.

It is an object of the present invention to provide an improved voltage converter. To achieve this goal, a voltage converter includes an inductive circuit that stores energy during inductive magnetization mode and delivers energy during inductive demagnetization mode, and at least two non-inverting branches to provide at least two non-inverting output voltages. And an inverting branch for providing an inverted output voltage, wherein the inverting and non-inverting branches are connected in parallel to the output of the inductive circuit, the inductive circuit transferring energy to the inverting branch and at least two non-inverting branches. Arranged to deliver to one of the branches, the inversion voltage and the corresponding non-inverting output voltage of one of the at least two non-inverting branches have a magnitude substantially equal to the opposite polarity.

The present invention can achieve significant savings in the required switch arrangement which enables the design of a more efficient and more cost-effective voltage converter by connecting the inverted branch to the output of the inductive circuit rather than to the output of the non-inverted branch. It is based on insight. The present invention is also based on the insight that the output voltages of the non-inverting and inverting branches are determined by the voltage clamp level available at the output of the inductive circuit so that it is no longer necessary to connect the inverting branch and the output of the non-inverting branch. I put it.

In another embodiment of the voltage converter according to the invention, the inverting branch comprises a capacitive circuit for storing the delivered energy during the inductive magnetization mode and discharging the delivered energy during the inductive magnetization mode. . The capacitor may preferably function as a battery which is first charged until the required voltage level is reached and subsequently decharged on demand.

In an embodiment of the voltage converter according to the invention, the capacitive circuit is arranged to receive the transferred energy through the input of the capacitive circuit while the output of the capacitive circuit is connected to the ground voltage, the input of which is connected to the ground voltage. It is arranged to discharge energy through its output stage while connected. This embodiment has the effect of providing a convenient way to reverse the polarity of the voltage across the capacitor.

In another embodiment of the voltage converter according to the invention, the voltage converter is configured to connect the input terminal (In) and the output terminal (Out) of the capacitive circuit to the ground voltage (GND) respectively during the inductive magnetization mode and the demagnetization mode, respectively. A first and a second switch device. By the first and second switch devices, the capacitive circuit can be easily charged and decharged in a controlled manner.

In an embodiment of the voltage converter according to the invention, the voltage converter comprises a voltage down converter circuit through which an input voltage is applied to the inductive circuit. In addition, the amount of charge generated in the inductive circuit and the output voltage of the voltage converter can be controlled.

In an embodiment of the voltage converter according to the invention, the voltage down converter circuit comprises a third switch device and a fourth switch device for alternately applying an input voltage and a ground voltage to the inductive circuit. This embodiment has the advantage that the amount of voltage down converted can be determined by the duty cycle of the third switch device and the fourth switch device. This makes it possible to obtain a programmable voltage down converter circuit.

In an embodiment of the voltage converter according to the invention, at least one of the at least two branches comprises an additional switch device for activating the branch. By this further switch device, the energy flow from the inductive circuit can be controlled. This means that if only an additional switch device is closed, energy will be transferred to the branch. Also, if this additional switch device is closed, the magnitude of the clamp voltage of the inverted branch will be substantially equal to the magnitude of the clamp voltage of the activated non-inverted branch.

In another embodiment of the voltage converter according to the invention, the voltage converter further comprises control means for controlling the switch devices. By controlling the switch, the operation and response of the voltage converter can be controlled.

The above and other aspects of the present invention will be described through the following drawings.

1 is a view showing a voltage converter according to the prior art.

2 shows the magnetizing current I _L through the inductor L in a voltage converter of the prior art.

FIG. 3 shows the voltage drop U _L across the inductor L in the voltage converter of the prior art.

4 shows a capacitive DCDC inverter.

5 illustrates a voltage converter including a capacitive DCDC inverter according to the prior art.

6 illustrates a voltage converter including a capacitive DCDC inverter according to the present invention.

7 illustrates a switching sequence of a voltage converter including a capacitive DCDC inverter according to the present invention.

8 shows another voltage converter according to the prior art including an input voltage reducing means.

1 illustrates a conventional voltage converter for converting an input voltage Vi into three clamp voltages V _a , V _b , V _c . In FIG. 1, V _a > V _b > V _c . Resistors R _L1 , R _L2 , R _L3 represent the load of the voltage converter. Clamp voltage V _a, V _b, V _c is produced in accordance with methods generally known in the art. For example, by controlling the duty cycles of inductive magnetization mode and demagnetization mode in response to measuring clamp voltages V _a , V _b , V _c or measuring current through circuit loads R _L1 , R _L2 , R _L3 . do.

During inductive magnetization mode, the switch S _L is closed (conductive state), while D1, S5 and S6 are in a non-conductive state. Clearly, the magnetizing current I _L is equal to I ₁ . One skilled in the art can easily prove that I ₁ is equal to I ₁ = (V _i / L) * t, where L represents the inductance of the inductor L and t represents time. Thus, the magnetization current I _L will continue to increase up to I _L equal to I max over time, as shown by curve 20 in FIG. 2. It can easily be demonstrated that during inductive magnetization mode the current I _L transfers the amount of energy E equal to E = 1/2 * L * Imax ² to the inductive circuit L.

During the inductive demagnetization mode, the switch S _L is opened while at the same time one of the switching elements D1, S5, S6 is brought into a conductive state. The energy E = 1/2 * L * Imax ² stored in this way is distributed over the output branch 12, 13 or 14. By way of example, FIG. 1 assumes that only S5 is in a conductive state such that I _L = I ₂ . It is generally known in the art that the inductor L is resistant to rapid current changes. Thus, it can be easily demonstrated that I ₂ will decrease linearly as shown in curve 22 of FIG. 2 starting at I max. The angle α of the lamp 22 of FIG. 2 is determined by L * dI _L / dt = (V _i -V _b + V _D2 ), where the angle of the lamp 22 is mainly determined by the output voltage V _b . .

V _b may be expressed as V _b = V _i -L * d _{L L} / dt + V _D2 . During inductive demagnetization mode, the voltage across inductor L of L * dI _L / dt volts will have a negative polarity, which is shown, for example, in curve 32 of FIG. However, it is clear that -L * dI _L / dt has a positive distribution with respect to the output voltage V _b . V _D2 represents the voltage drop across diode D2, which is typically between 0.3 and 0.7 volts depending on the technique used. Diodes D1, D2, D3 are provided to prevent current leakage from the output terminal of the voltage converter to the internal node 10. Diodes D1, D2, D3 can be omitted if switches S5, S6 are unidirectionally conductive, i.e., only conducting to the output at internal node 10. This is the case, for example, when the switches S5 and S6 are constituted by a pair of PMOS transistors connected in series. In this case the branch 12 must comprise a switch device. If switches S5 and S6 are open, current I ₂ will begin to flow through branch 12. If switch S5 is closed and S6 remains open, the voltage of V _b -V _D2 will be placed on internal node 10. Since this is _a voltage lower than V _a , diode D1 will be turned off and I ₂ will begin to flow through the second branch 13. Likewise, closing switch S6 _puts a voltage of V _c -V _D3 on internal node 10, which will turn off diodes D1 and D2. By operating the switches S _L , S5, and S6 in a controlled manner, the inductor L can be magnetized and demagnetized, and energy can be transferred from the inductor L to each of the branches 12, 13, 14. Capacitor C1 functions as a DC input buffer, which protects the input line from the high frequency switching input current and switching noise of the voltage converter. Capacitors C2, C3, C4 function as DC output buffers. This function first flattens the high frequency output current and ensures a continuous output voltage for a period of time when no charge is provided in the branch of the voltage converter. As a result of this, the voltage across capacitors C2, C3 and C4 will show some AC ripple. However, this is of little importance because the capacitors C2, C3, C4 are recharged at very high speed by the inductive circuit.

2 shows the magnetizing current I _L flowing through the inductor L. FIG. The rising edge 20 represents the charging or magnetization of the inductor (S _L is closed). During inductive maximal mode, the magnetizing current I _L increases until S _L is open. It is easy to prove that I _L is equal to V _i * t / L, where t represents time and L is the inductance of inductor L. Once S _L is open, current I _L is equal to I max and will represent falling edge 22 as shown in FIG. 2. This falling edge can be expressed as dI _L / dt = (V _i -V _out + V _D ) / L, where V _i represents the input voltage. Vout represents any of the output voltages V _a , V _b , V _c of FIG. 1, and V _D represents the voltage drop across diodes D1, D2, D3 when the diodes are in a conductive state.

3 shows the voltage drop U _L across the inductor L which can be expressed as U _L = L * dI _L / dt. This produces a negative polarity 32 of the voltage U _L for Blazers edge 22 of I _L rising edge 20 for thereby creating a positive polarity 30 of the voltage U _L, I _L of.

4 shows a DCDC capacitive voltage converter. Shown is a capacitor Cpump being charged by the input voltage source V _i. During charging, switches S4 and S2 are closed while switches S _L and S7 are open. Through this, the Cpump will be charged until the voltage drop across the Cpump becomes V _i and has the polarity as shown in FIG. 4. Once Cpump is fully charged, switches S4 and S2 ultimately open and switches S _L and S7 are closed. Therefore, Cpump is connected to the output capacitive voltage inverter and delivers an output voltage Vinv having a polarity opposite to have the same size as V _i. Capacitor Co is a DC output buffer that flattens the high frequency output power of the converter and provides the output voltage Vinv to the load of the capacitive DCDC inverter when the pump capacitor Cpump is recharged.

FIG. 5 shows a combination of the prior art DCDC voltage converter shown in FIG. 1 and the capacitive DCDC voltage inverter discussed in FIG. 4. The capacitor Cpump is connected to the output terminals of the branches 12, 13 and 14 by switches S4, S'4 and S "4 operating in an alternating manner. For example, by closing the switches S4 and S2, the pump capacitor Cpump is connected to the voltage V. _It is charged by _c . By closing switches S7 and S1 and opening switches S4, S'4, S "4 and S2, the output voltage Vinv becomes equal to -V _c .

6 illustrates a DCDC voltage converter according to the present invention. Shown is a capacitive DCDC inverter connected to the internal node 10. This charges the Cpump to the voltage available at node 10 during inductive demagnetization mode. As described above, this voltage is determined by the voltage drop across the input voltage _Vi and the inductor L. Clearly, the voltage drop across the inductor is determined by the currents I2 and I'2 derived therefrom during the demagnetization mode. This allows the output voltage Vinv to have substantially the same magnitude as any one of the clamp voltages V _a , V _b , V _c , depending on any of the non-inverting branches 12, 13, 14 being activated. By providing the control means 82, the duty cycle of the switches S1, S2, S5, S6, S7 can be controlled to influence the operation of the voltage converter. This embodiment provides the advantage that an extra limited amount of switch is required. In other words, switches S6 and S7 provide the advantage of making the circuit easier to integrate with low cost and low requirements for control of the switch.

7 shows a switching cycle for controlling the switches S1, S6, S7 of FIG. 6 by way of example. It is assumed that energy is provided to the non-inverting branch 14 (delivered on demand). This means that switches S5 and S2 are closed and S6 and S7 remain open. It will be apparent to those skilled in the art that the voltage level of the node 10 substantially corresponds to the clamp voltage V _b . This means that the voltage across Cpump will also be V _b . During the next inductive magnetization mode 72, the switches S1 and S7 are closed so that the current I ₁ will start flowing to charge the inductor L with energy while the output voltage of the inverted branch Vinv becomes -V _b . Once Cpump is connected to the output of the inverted branch, it is clear that the voltage across the capacitor Cpump will decrease somewhat. Thus, during the next inductive demagnetization mode, switches S1 and S7 are opened again and S6 is closed. This causes the Cpump to refill with energy, so the voltage drop of V _b will again appear across the capacitor Cpump.

8 shows a DCDC voltage converter, by means of switches S3 and S4, the ground voltage GND and the input voltage V _i are alternately connected to the inductor L to reduce the average value of the input voltage V _i . It is apparent to those skilled in the art that this reduction in input value is effectively used to influence the output voltage of the DCDC voltage converter.

It is to be noted that the above-described embodiments illustrate rather than limit the invention, and those skilled in the art will be able to design many other embodiments within the scope of the appended claims. The word "comprising" does not exclude the presence of elements or steps listed in the claims. A singular element does not exclude a plurality of such elements. Reference to certain means by mutually different dependent claims does not indicate that a combination of such means cannot be used.

Claims (10)

In a voltage converter, An inductive circuit (L) for storing energy during the inductive magnetization mode and transferring energy during the inductive magnetization mode; At least two non-inverting branches 12, 13, 14 for providing at least two non-inverting output voltages Va, Vb, Vc, An inversion branch 15 for providing an inverted output voltage, The inverting 15 and non-inverting branches 12, 13, 14 are connected side by side to the output terminal 10 of the inductive circuit L, the inductive circuit 15 and the at least two branches. Arranged to transfer energy to one of the non-inverting branches 12, 13, 14 of the inverted voltage Vinv and the corresponding non-inverting output voltage of one of the at least two non-inverting branches 12, 13, 14 (Va, Vb, Vc) have opposite polarities and have substantially the same magnitude Voltage converter. The method of claim 1, The inverting branch (15) comprises a capacitive circuit for storing energy delivered during the inductive magnetization mode and discharging the delivered energy during the inductive magnetization mode. The method of claim 2, The capacitive circuit Cump is arranged to receive the transferred energy through the input terminal In of the capacitive circuit Cpump while the output terminal Out of the capacitive circuit is connected to ground voltage GND. And the capacitive circuit (Cpump) is also arranged to discharge energy through the output (Out) while the input (In) is connected to the ground voltage (GND). The method of claim 3, wherein And first and second switch devices for respectively connecting the input terminal (In) and the output terminal (Out) of the capacitive circuit to ground voltage (GND) during the inductive magnetization mode and during the demagnetization mode. The method of claim 1, The voltage converter comprises a voltage down converter circuit (80) through which an input voltage (V _i ) is applied to the inductive circuit (L). The method of claim 5, The voltage down converter circuit 80 comprises a third and fourth switching devices (S3, S4) for applying an input voltage (V _i) and a ground voltage (GND) to the inductive circuit (L) alternately Voltage converter. The method of claim 1, At least one of said at least two branches (12, 13, 14) comprises an additional switch arrangement (S5, S6) for activating said branch. The method according to any one of claims 1 to 7, The voltage converter comprises control means (82) for controlling the switch device. A power management device comprising the voltage converter according to any one of claims 1 to 8. A mobile device comprising the power device according to claim 7.

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